Firearm



FIREARM Filed Aug. 3, 1942 [L i I Y y i i l l I 1 i 5 CharlesE-IE|E111E1'5 E11 Patented Apr. 3, 1945 FIREARM Charles E. Balleisen,United States Army, Philadelphia, Pa.

Application August 3, 1942, Serial No. 453,423

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) 4 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to firearms.

An object of this invention is to provide a firearm of the type shown inBrowning Patent 1,293,021, with means incorporated therein for assuringa minimum amount of gun failure due to cartridge case extractiondifiiculties.

Another object of the invention is to provide a firearm of the U. S.standard Browning machine gun type, with means therein for assuring thatthe breech bolt and cartridge are in their farthermost rear lockedpositions with respect to the barrel before the cartridge is fired.

Another object of this invention is to provide means in a firearm forassuring a minimum amount of gun failure due to excessive deformation offired cartridge cases.

Another object of this invention is to provide means in a firearm forassuring minimum and machine gun.

Fig. 2 is an enlarged view of modified bolt and barrel extension memberssimilar to those shown In Fig. 1 and showing in greater detail theassembly of spring means between the bolt and barrel extension,

Fig. 3 is a section taken substantially on line 3-3 of Fig. 2.

Fig. 4 is a view similar to Fig. 2 showing a modified spring means.

Fig. 5 is a detail of a modified spring member of rubber or similarresilient material.

Reference will be had to the disclosure in the The resilspring R so asto move the breech bolt E in its breech bolt has moved sufficientlyrearward to take up all .play in the parts.

In adjusting the Browning machine gun, it is necessary to thread thebarrel B into the barrel extension C so far that, when the bolt E is inits forward locked position, no play between the bolt E and barrelextension C exists. This operation is commonly known as adjusting theheadspace. It has been found when play is permitted between thesecomponents, failure of the cartridge case by axial rupture, that isseparation axially, is frequent. This failure is usually attributed toexcess headspace, that is, a too deep cartridge chamber, even when theheadspace is only a few thousandths of an inch in eicess of commonlyaccepted values. It is believed however, that this excess headspace isnot he true cause of ruptures, as fin'ngs have been 0 ducted, innon-automatic guns when the readspace was approximately thousandths f aninch in excess, without failure of the car ridgecase. These firings wereconducted wit the same lot of cartridges which had shown fl u es in amachine gun. Other known instanct exist where the play was veryaccurately adjusted, but

with a relatively large headspace, no pa t e case failures occurred.

In explanation of the above perfornance applicant believes the cause ofcartridge'case fa11- ure resides in lost motion between thebolt E andbarrel B when the bolt is not held firmly and against rearward movementin its licked p tion: and this lost motion is attributed to disparity inmating dimensions presen; when, guns are made by production methods. onthis basis, it is possible, when the mechanism'goes forward prior tofiring, for the bolt and cartridge to be jolted into and remain in theirfai'thermost forward positions with respect to the barrel. Upon firing,the propellant gas causes the cartridge case to expand and the forwardend of the cartridge'case' being thinnest expands first and grips thechamber and thus releases the bullet; the ammunition cartridge gasesthen push the cartridge case to the rear. If the bolt E is not rigidlysupported, it will move relative to the barrel B, and the cartridge casewill elongate longitudinally as its rear end is pushed against. the faceof the bolt E while the front end is gripped by the barrel chamber wall.,As, however, the walls of the cartridge case are cold worked and cannotwithstand much distortion, the case may separate into two pieces.

It is important that the cartridge case be held firmly in the barrel, 1.e., no movement of the breech bolt E relative to barrel B should resultwhen and as the cartridge is fired. Herein lies one important phase ofthe invention, namely, to provide means for firmly supporting thecartridge case against the breech bolt face and to secure the: bolt. Eagainst movement relative to the barrel B" so that gas-pressure'can actonly to deform the shoulder and neck of the cartridge case whereby thoseelements tend to conform to the shape of the barrel chamber.

From the foregoing description it is apparent that the rupturing ofcartridge cases. may be prevented by insuring that the cartridge caseand bolt are in their rearmost lock position before firing. This can beaccomplished by means of springs or other expanding devicesv of, lowstrength, which strength need only be sufficient to overcome the inertiaand friction of the: parts to be moved to their rearmosti position. andthe initial, force of the reaction spring R. These spring elements maybe placed wherever the configuration of the parts conveniently permits;however, it appears most practical toplace them within the rear end'of.the modified barrel extension C as seen in Fig. 2 to act with the reardownwardextension of the modified breech bolt E,'. It. is noted that themodified barrel extension C and'modified bolt E have structure similarto that of corresponding elements in Fig. 1 and'in the Browning Patent1,293,021 and have identical'functions. A pair of helical springs I0, II are shown in Fig. 3 but it is apparent that one or a plurality of leafsprings l2; Fig. 4, may be iubstitut'ed for the helical springs I, I I,or small Wlinders l3 (Fig. 5) of highly; elastic material such as rubbermay also be employed instead of cyindrical helical springs I, H.

n Figs. 2 and 3thesprings H]; H are received ant held. in barrelextension recesses 14, I5. In Fig.4 curled leaf spring 12 is held in thedownwarlly extending portion of breech block E.

Inzhe prior art practice as seen in the Brown- Patent. 1,293,021,,thereaction spring R tends to mme the boltE as far forward as, possible andbarrel extension C is moved as far forward as possible by the tension ofthe spring on the pisn Q- It is quite apparent that no means arediscloses in. the Browning Patent 1,293,021 for takingu play andassuring positive engagement,

betweenv the breech bolt E and. locking block N; the. spring devices orresilient means which overcome the effect of reaction spring R assurepositive engaglment of the bolt E against locking blo ck.N ani thuspositively maintain, the bolt E andlcartridge in. their farthermore rearposition with respect to the barrel 3.

I claim: a

1.. In:a firearm having a recoiling barrel and a rearwardlyexzendingbarrel extension, a breech bolt; means-for locking the breechbolt and barrelextension together against relative axial movementintheir firingposition said locking means of the type subject to, axialplay when in locked position, and a spring urging. the breech boltforward; the. improvement comprising, resilient means interposedbetween. the breech bolt and barrel extension and bearing, directly oneach,

and stronger than said spring when the latter is in expanded condition,said stronger resilient means being adapted to take up play between thebreech bolt and barrel extension incident to the bolt locking means whensaid bolt and extension are in firing. position, thus assuring that whensaid bolt and extension are in such position, the cartridge and bolt arein their furthermost rear position with respect to the barrel at thetime of firing the cartridge.

2. In a, firearm having a breech bolt, a recoiling barrel, a barrelextension, a locking block carried by the extension for locking the boltand extension together against relative axial movement in firingposition said locking means of the type subject to axial play when inlocked position, means for actuating the block to effect such 1ockingduring the forward movement of said bolt and extension, and a breechbolt spring urging said bolt forward; the improvement comprising aseparate spring interposedbetween the breech bolt and the barrelextension and'bearing directly on each, and stronger than the breechbolt spring in its expanded condition and" adapted to take up playbetween the breech bolt and barrel extension incident to the lockingblock when in locked position, thereby assuring engagement between thebolt and the barrel extension and the maintenance of the bolt andcartridge'in the barrel in their furthermore rear position with respecttothe barrel at thetime of firing the cartridge.

3. In a firearm'having: a -recoiling' barrel having a cartridge casechamber allowingexpansion of the cartridge case within' the limitsincident to the thermal condition in the cartridge case chamber when thecartridge is fired and a rearwardly extending barrel extension, a breechbolt, and means for locking. the: breech bolt and barrelextensiontogether in their firing positionsaid locking means of the type' subjectto axial play when in locked position, the improvement comprisingresilient means directly engaging the barrel: extension: and: bolt andurging the latter to its furthermost rear position by taking up the 2play inthe bolt locking means, thus assuring that the cartridge as wellas the bolt are in their Iurthermost rear position withrespect to thebarrel at the time of firing the cartridge.

4. In a firearm, a recoiling barrel having a chamber for insertion of acartridge and-a barrel extension having a rearwardly disposed face, abreech bolt slidablymounted in. thebarrel extension, a recoil springurging saidlbolt to firing position, said bolthaving a portion extendingsubstantially parallel with the barrel extension face, bolt lockingmeans carried by the barrel extension for locking the bolt and barrelextension together in firing position said locking means of the typesubject to axial play when in locked position, and a spring stronger.than the recoilspring when said recoil spring is iniexpanded position,said spring being interposed between said bolt portion and barrelextension face, bearing directly on each, and urging the bolttolitsfurthermost rear position against the bolt locking means at thetimeof firing the cartridge.

CHARLES E. BALLEISEN.

